I just bought a 2000 xj classic 4.0 yesterday with 83,000 miles on it and when I looked the vehicle over before buying I checked all the fuilds and they all seemed good. I drove it 200 miles home and was changing the valve cover gasket and when I pulled the cover there was a milky light brown sludge in it. So I checked the radiator and the same brownish sludge. It didnt overheat or get hot on the drive home but it was a little low on antifreeze. Could I really have that bad of luck and blew the head gasket on the drive home?

 

Did you check the color of the antifreeze before you got it? maybe the po didnt flush the cooling system.

 

I'd say chances are that the PO knew the problem! You may be stuck with a Big Headache! Good Luck!

 

It could be a headgasket. But it very possibly is a cracked head. The 00-01 have a defect between cylinders 3-4 on the 0331 head. It is NOT uncommon for it to crack.

You need to verify this ASAP. Best to remove the valve cover and with a pressurized cooling system, look for seepage between 3-4.

 

Does anyone have a idea on how much this will run me? And if I do it myself which cylinder head should I buy to replace it with if this model years where prone to failure. I am hoping it will be a bad head gasket and not a cracked head!

 

Here is a very good thread on the 0331 head issue. Required reading for you..

http://www.jeepsunlimited.com/forums...d.php?t=391831

 

Well it looks like I will need a head regardless of if it is cracked now or just the head gasket. I didnt realize the 2000-2001 4.0 had head issues I guess I should of joined this forum before I bought itBut on the upside I found a 2004 wrangler head for $250 so it looks like I will be doing it myself.

 

The 2004 Wrangler head is a TUPY (different foundry/design) and will work fine.

The wildcard question for you is how long has it been cracked. Even a small amount of coolant mixed with the oil can damage the engine bearings pretty quickly.

What oil pressure are you running at? You may even want to drop the oil pan and sample some bearing clearances with plastigage.

 

At idle about 38-40 as soon as I found out I drained the oil and took off the valve cover and cleaned it also. Ok would I have to pull the oil pan too to clean the gunk out of there too? Ive been out this morning flushing out the radiator.

 

I would try not to run it at all if you suspect a blown HG or cracked head.
From what I read the 0031 usually crack between the #3 and #4 cylinders and don't always mix coolant with oil so you may be ok as far as that goes but I would pull the head or take it somewhere to have it diagnosed before running it.

 

Brown junk is oil + coolant.

Probably have a cracked head. Even if it is "just" a blown head gasket, get rid of the 0331 head while you have it off.

Previous owner probably knew about this. That's why they sold it.

Flushing the radiator at this point is probably a waste. The stuff will just get in there again.

 

Pulled it apart today and it ended up being just the head gasket but I went ahead and bought a newer 0331 head of a 2004. There wasn't much of the milky gunk in the head or jackets so I think I caught it early. Should I still pull the oilpan and check for more oil/coolant?

 

Got my new Cylinder Head today hopefully this weekend it will back up and running!

 

Got it back up and running. I have a question about rocker torque specs the Haynes manual says 19ftbs and I saw some threads on here saying to do 22-24ftbs. I did them at 20 and they seem a little noiser than before

 

The 2000 Service Manual says:

Rocker Arm Assembly to
Cylinder Head—Capscrews 30 Nm or 21 Ft lbs

You can download a copy of the service manual off of Great Lakes XJ Tech forum. I highly recommend it...

Greg